Training system and method using a dynamic perturbation platform

ABSTRACT

A new apparatus, system and method for fall prevention training is provided that delivers, studies and analyzes the biomechanics of a disturbance event, such as a slip or trip incident, so that an appropriate response can be executed by the person to reduce or eliminate the number of falls experienced. The apparatus includes a platform that delivers a disturbance event in less than about 500 ms and preferably in the range of about 100 ms to about 200 ms. The method includes a unique protocol for fall prevention training using the apparatus. The disturbance event can create instability in the joint of the individual. An individual&#39;s walking gait can be monitored with the portions thereof detected. A disturbance event can be triggered when a given portion of the walking gait is detected. Also, the disturbance even can be triggered manually, at preset intervals or according to preset script.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of Ser. No. 13/182,575, filed Jul.14, 2011, which is a continuation-in-part of Ser. No. 11/294,942, filedDec. 6, 2005 (now U.S. Pat. No. 7,980,856, dated Jul. 19, 2011) which isrelated to and claims priority from earlier filed provisional patentapplication Ser. No. 60/675,768, filed Apr. 28, 2005, all of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention generally relates to the human performance, sportsmedicine and medical rehabilitation field. More specifically, thepresent invention relates to a method for fall prevention training usinga dynamic perturbation platform to improve the study and research of thebiomechanics of trip, slip, and laterally-directed postural disturbancesby a person and the step recovery thereof. Additionally, the presentinvention relates to human performance, injury prevention andneuromuscular training using a dynamic perturbation platform to trainstep responses to anterior, posterior or laterally-directed posturalperturbations. Additionally, the present invention relates toneuromuscular training around any body joint response to dynamicperturbations of the body joint or multiple body joints.

It is well known in the medical field that a slip or trip during walkingor standing can lead to a fall and be a serious cause of injury. This isparticularly problematic for elderly people where such injuries are aleading cause of mortality. It is well known that many of these injuriescan be prevented or their severity lessened if the person uses aneffective strategy and technique for responding to a fall situation.Therapeutic Interventions can reduce the likelihood of a fall from adisturbance event, such as a trip or slip incident. Exercise andphysical training can be used to develop strength, balance andcoordination. Also, the person's environment can be changed to removeobstacles and other hazards that can cause a slip or trip. Bars and handrails can be provided to assist walking and standing. Padded garmentscan be worn by the person to reduce the injury caused by the slip orfall.

An alternative approach is to study why a person falls and train them tobetter recover from a slip or trip to avoid a fall by taking acorrective step response. Therefore, the biomechanics of a slip or fallcan be studied to better understand clinically effective ways to preventsuch falls due to a slip or trip. As part of the study and analysis ofdisturbance events, including slip and trip incidents, it is highlydesirable to be able to monitor a slip or fall incident in a controlledenvironment to produce data that is usable for effective training tohelp persons adapt their strategy for responding to a slip or tripincident.

It is also well known in the medical field that dynamic stability of abody joint is important for injury prevention. The ligaments and tendonsand musculature that cross body joints prevent excessive motion of thejoint that leads to injury of the structures both within and surroundingthe joint. The benefits of neuromuscular training are known to provideincreased endurance, positional awareness, performance and reduction ininjury risk.

Specifically with respect to the knee, neuromuscular training alsoincreases dynamic knee stiffness, dynamic knee stability, and athleteagility. Human locomotion uses sensory information and motor reflex tomodulate pre-programmed motor control patterns in order to adapt tounexpected changes in the external environment. Proprioceptiveinformation is used to maintain postural and joint stability. In humanlocomotion there are major kinematic events where joint stability mightbe needed most. These events differ for walking and running. All aroundthe body, joint stability is attributed to joint stiffness that occurswith co-contraction of antagonistic muscles around a joint. Increasedjoint stiffness is believed to resist sudden joint displacements moreeffectively reducing the incidence of joint subluxation.

More specifically, it is well known in the medical field that ligamentand other soft tissue injuries are a significant problem among peoplewho engage in cutting, jumping, and pivoting activities, particularlyyoung athletes and women. One ligament that is often injured, forexample, is the anterior cruciate ligament (ACL) in the knee. For ACLinjured athletes, neuromuscular training has improved functional outcomeand increased likelihood of return to previous activity levels withdecreased likelihood of knee giving way episodes. Similar effects andresults can occur following soft tissue injuries to other structures andjoints in the body, and are not limited to the ACL.

Following ACL or other soft tissue injury, both surgical andnon-surgical treatment options exist, with the ultimate goal ofregaining dynamic joint stability, and in the case of the knee joint,normal knee kinematics, and symmetrical quadriceps strength betweenlegs. These outcomes are critical for full return of dynamic kneefunction and returning to pre-injury activity levels, as well as forpreventing additional injury to the cartilage and the meniscus in theknee which might lead to an increased likelihood of osteoarthritis (OA).

Laboratory research has demonstrated clinically relevant effects ofperturbation of support surface training for both ACL-deficient (ACL-D)and ACL-reconstructed (ACL-R) populations, particularly in females.Currently, perturbation training systems and methods are limited tobalance boards that are manually pushed or pulled by physicaltherapists, and may not simulate real-life or sport-specificperturbations. Specifically, balance boards do not allow forperturbations that occur during an actual step. The manual perturbationmethod does not allow for repeatable timing of perturbations at specificphases of the gait cycle, nor can the perturbations be delivered in lessthan 500 ms.

ACL injuries are extremely common, with approximately 100,000-250,000ACL reconstructions being performed annually in the United States. Whilemales comprise a majority of all ACL injuries females are at 3-6×greater risk of suffering an ACL rupture than males. Rehabilitation istime-consuming; time from injury to completing postoperativerehabilitation can range from a few months to a year or more, andsurgical intervention does not ensure a return to previous activitylevels. At an estimated cost of $17,000 per ACL reconstruction andphysical therapy services, expenses for this injury may exceed $1Billion annually in the United States alone.

The ACL plays a principal role in maintaining normal knee function andstability. Quadriceps strength deficits and ACL rupture independentlyincrease the likelihood of developing knee osteoarthritis (OA). ACLinjury often leads to knee instability, quadriceps weakness, gaitdeviations, and post-traumatic OA. Aberrant movement and abnormalmuscular strategies are common in the ACL-deficient athlete.Snyder-Mackler and colleagues developed and validated a functionalscreening examination as a clinical tool to identify those who have thepotential to compensate well for the injury (potential-copers).Non-candidates, or non-copers, were classified by their poor functionalperformance and episodes of knee instability. Recurrent give wayepisodes of the ACL deficient knee in non-copers are likely due to theirinability to stabilize their injured knee with appropriate muscleactivity. Rudolph et al. defined the neuromuscular behaviors of ACLdeficient athletes, and found an ineffective knee stiffening strategycharacteristic of non-copers. Non-copers excessively co-contract theirthigh and hamstring muscle and truncate their knee motion which mayfurther exacerbate the alterations in joint loading and causedegenerative changes to the underlying cartilage. Persons who presentwith a combination of aberrant gait patterns, quadriceps weakness, andknee instability in response to an ACL rupture are at significantlyincreased risk of developing post-traumatic knee OA. Therefore, theimportance of restoring normal gait kinematics and kinetics in thispopulation has been underscored by many research groups.

Quadriceps weakness and knee instability can also lead to a kneestiffening strategy in an attempt to improve stability during dynamicactivities, such as walking, jogging, stair climbing, and balancing onone limb. This strategy is used predominantly by athletes who arenon-copers. Hartigan et al. demonstrated that perturbation training wasable to restore symmetric knee excursions in this cohort, something thatwas not achieved by strength training alone. Again, this perturbationtraining was performed manually.

Clinical rehabilitation paradigms for non-operative treatment andpost-operative rehabilitation following ACL rupture focus on reducingjoint effusion, increasing knee range of motion, increasing quadricepsand hamstring muscle strength, functional activity education andtraining, agility training, and protective bracing. However, theseapproaches may only be successful for patients that are more sedentaryor are willing to modify their physical activity levels. Common clinicaltechniques used during rehabilitation after ACL reconstruction are oftenlimited to strength training, task-specific exercises, and staticbalance exercises. For athletes, proper coordination of muscle activityis also critical for improving dynamic knee stability and ultimately,sport performance.

After ACL injury, the quadriceps and hamstrings have diminished abilityto dynamically stabilize the knee due to disruption of themechanoreceptors in and around the knee joint. Task-specific manualperturbation training has been shown to enhance the restoration ofdynamic stability in ACL deficient patients. Factors that are modulatedduring perturbation training include predictability, speed, direction,amplitude, and intensity of the perturbation. Snyder-Mackler andcolleagues combine progressively challenging manual perturbationtraining together with sport-specific task training in order to achieveimprovements in dynamic knee stability. Snyder-Mackler and otherresearchers published the results of their studies and have demonstratedthe following:

-   -   Superior return to functional activity in potential copers when        compared to standard rehab programs (e.g. strength training).        93% of patients using manual perturbation training returned to        high-level activity without episodes of giving way. In contrast,        only 50% of those who received traditional therapy returned to        high-level activity.    -   Patients undergoing perturbation training increased their        likelihood of success (i.e. no episodes of knee giving way) by        4.9× when compared to standard treatments, including strength        and agility training.    -   Improved dynamic knee stability in ACL deficient patients        through improved neuromuscular changes.    -   Increased Lysholm Knee Rating Scale scores compared to subjects        who received standard strength training rehabilitation.    -   Normal quadriceps and hamstring activations and increased active        stiffness. These changes may prophylactically reduce the risk of        biomechanical strain injury in high-risk populations.    -   Manual perturbation training significantly improved lower leg        dynamic muscle control in healthy young athletes. Young women        responded favorably to perturbation training by mitigating their        quadriceps dominance and activating their hamstrings earlier in        stance, thus restoring healthier muscle activation patterns.    -   Manual perturbation training in conjunction with strength        training improved dynamic knee stability, knee range of motion        during midstance, and limb symmetry compared to strength        training alone.

While manual perturbation paradigms are effective at resolving aberrantneuromuscular strategies in ACL-deficient individuals, the time requiredto administer the treatment may not allow the therapist time to addressother patient impairments. Manual perturbation training does not addressthe idea of providing the perturbation during the walking cycle or whilerunning. Additionally, manual perturbation training may not allow fortimed perturbations at specific phases of the gait cycle, or at specificjoint positions, velocities or joint forces. Manual perturbation do notallow for timed and controlled perturbations at specific velocities of agiven joint.

Conversely, the present invention overcomes the limitations of manualperturbation methods. In the present invention, perturbations can betriggered manually, or, when desired, on a timed basis or other pre-setschedule. The timing of perturbations can be based on intrinsicphysiologic factors, such as phase of the gait cycle, position, velocityor acceleration of a limb or joint. The timing of perturbations based onspecific phases of gait, perturbation and automatic speed adjustmentscan be based on the timing and phasing of braking and propulsion of thelimb being monitored.

Additionally, the timing of perturbations can be based on extrinsicfactors. There exists relationships among neuromuscular timing andexternal cues or triggers. Existing systems such as Nike+, a product ofNike, Inc., modify target exercise parameters based on music selected.Alternatively, it is possible to modulate the speed, pitch, volume,beat, and other rhythmic patterns of music played or presented to a useras a function of the exercise being performed or prescribed. In asimilar fashion, visual stimuli such as video presentations or tactilestimuli or other external stimuli can be used in either an excitatory orfeedback mode in conjunction with neuromuscular training. Suchinteractions between external stimuli and neuromuscular trainingspecifically are lacking in the prior art.

The present invention can be used to address and prevent a wide range ofjoint related diseases and injuries, such as but not limited toosteoarthritis and ankle sprains. The present invention is not limitedto preventing joint-related diseases and injuries in the lowerextremity. There is a also a need to be able to provide controlledperturbations to portions of the body other than those in the lowerextremity. For example, there is a need to be able to deliver controlledperturbations to areas of the upper body, such as the elbow, wrist orshoulder for the prevention of disease and injury to those regions.

In view of the foregoing, there is a need for a system that canaccurately simulate a slip or tripping incident. There is a need for asystem that can measure the biomechanics of a slip or tripping incidentto further assist a person to better respond to the incident to avoid afall. There is a further need for an apparatus that is well-suited tomeasure such biomechanics. There is a need for an apparatus that cansimulate various trip and slip scenarios that could lead to a fall so anappropriate response can be developed. There is a need for an apparatusand system that can better train a person to avoid a fall following atrip or slip incident. Moreover, there is a need for a method for fallprevention training to better prepare a person for a disturbance event,including, a slip, trip or fall, to avoid injury or death.

In view of the foregoing, there is a need for a system that can providetask-specific, neuromuscular, dynamic perturbation training to preventinjury to the soft tissues surrounding body joints There is a need for asystem that provides perturbations that induce joint instability thatrequires a neuromuscular response to retain, maintain or retrainintrinsic body joint stabilization There is a need for a system thatprovides task-specific, neuromuscular, dynamic perturbation training toprevent the development and progression of osteoarthritis and otherjoint-related diseases. There is a need for a system to provideperturbations during the stance phase of the gait cycle duringlocomotion. There is a need for a system to provide perturbations duringthe different phases of stance in the gait cycle to elicit a specificjoint response. There is a need for a system to provide perturbationsthat are controlled and triggered by detecting the braking, midstanceand propulsion phases of control for a given joint. There is a need fora system to provide perturbations to a joint at a preferred kinematicposition, velocity, or loading condition to elicit and train a specificjoint response. There is a need for a system to provide modulation ofthe stretch reflex to prevent ankle sprains. There is a need for asystem that detects the different phases of the gait cycle, includingbut not limited to the stance phase, which also includes the braking,midstance, and propulsion phase, and which provides a trigger fordelivering the perturbation. There is a need for a system that providesaperiodic perturbations to challenge and train the joint response toperturbations that occur during daily living or during sportingactivity. There is a need for a system to provide perturbations duringathlete training or physical therapy where the perturbations aredelivered automatically, and in some cases repeatedly, without anymanual intervention from another individual or medical provider.

There is a need for a system that can provide controlled perturbationsto any part of the body, including the elbow, wrist and shoulder to helptrain response to such perturbations and prevent disease and injury tothose regions. There is a need for a system that can deliverperturbations very quickly and in an automated and controlled fashion toany part, portion or region of the body.

There is a need for a system to provide perturbations during the stancephase of the gait cycle that are synchronized with musical cues andother external stimuli. There is a further need for a system to provideperturbations of varying magnitude, direction and duration that aregenerated automatically based on the timing of music driving the system.There is a need for a system that selects music to be presented to auser based on the perturbation profile selected for a givenneuromuscular training activity There is a need for a system to provideperturbations that stimulates and trains braking and propulsion controlfor the joint.

SUMMARY OF THE INVENTION

The present invention preserves the advantages of prior art fallprevention training systems and methods associated therewith. Inaddition, it provides new advantages not found in currently availablefall prevention training systems and methods and overcomes manydisadvantages of such currently available systems and methods. Inaddition, it provides new advantages not found in current injuryprevention and neuromuscular training systems and methods and overcomesmany disadvantages of such currently available systems and methods.

In accordance with the present invention, a new apparatus and system isprovided that studies and analyzes the biomechanics of a disturbanceevent, such as a slip or trip incident or other disturbance to a part ofthe body, so that an appropriate response can be executed by the personto reduce or eliminate the number of falls or injury to the body partexperienced both in real life and in the simulation/disturbance event.With this new apparatus, system and method, a new and novel method forfall and injury prevention training can be delivered which is superiorto training methods known in the prior art.

The present invention uses a new and unique disturbance event simulationapparatus. The apparatus, in accordance with the present invention, maybe in the form of a perturbation platform is provided which is movableto create a disturbance event that induces a response from anindividual. Sensors are located proximate to the individual and theplatform with data being outputted from the sensors. A device isprovided for collecting and storing the data during the disturbanceevent. There is also a device for outputting the data so that it may beviewed and studied. The apparatus may also be a device, such as one thatis mounted to a wall, that delivers a perturbation to a part of theperson's body, such as a wrist, elbow and shoulder.

Preferably, the perturbation device, such as a platform, is movable tocreate the disturbance event in less than 500 ms and more preferably inthe range of about 100 ms to about 200 ms. In the platform example, itis also preferably a bi-directional motorized belt. Still further, twobi-directional belts can be provided in this embodiment. Also, theapparatus is capable of introducing an obstacle positioned proximate tothe platform to induce the response from the individual to thedisturbance event. The obstacle, for example, can be a light beam, athree-dimensional object or a hologram.

In accordance with the present invention regarding delivering adisturbance event to a person in a walking gait, an embodiment inprovided with a new apparatus and method that monitors the phase of thegait cycle for an individual standing or ambulating on the apparatus andwhich actuates the biomechanics of a disturbance event, so that anappropriate response can be executed by the person to improve measurablequantities such as dynamic stability or improved neuromuscular responsethat have been linked to ACL injury, OA, and joint instabilities. Withthis new apparatus, system and method, a new and novel method fordynamic neuromuscular training can be delivered which is superior totraining methods known in the prior art. The current invention improveson the existing systems by delivering systematic, progressiveperturbations while, if desired, simultaneously recording relevanttraining data. The perturbations may be timed to events in the gaitcycle, such as but not limited to heelstrike or toeoff. Theperturbations may be programmed to occur on every occurrence of such agait cycle event, or at multiples of such a gait cycle event, or at arandom number of occurrences of such a gait cycle event, Additionally,the perturbations may occur randomly but not during a specific gaitcycle event.

The current invention provides a system for perturbations that inducejoint instability in one or more body joints, individually orsimultaneously, and not limited to lower extremity. This can include thespine. When the perturbation is provided to the lower extremity, thetiming of the perturbation within the gait cycle at which theperturbation is induced and the magnitude of the perturbation may affectbody joints in different ways, including both the magnitude andactivation patterns of the musculature around the joints, andsubsequently the response of the body, such as ankle flexion, kneeflexion, hip flexion, trunk flexion, or a step response.

The present invention can also be modified to address joints that arenot in the lower extremity or associated directly with walking and fallprevention. The present invention is envisioned to include an embodimentwhere a perturbation device is provided, such as mounted to a wall forexample, that delivers a perturbation to a part of the body that is notin the lower extremity, such as the wrist, elbow or shoulder. The personmay reach out and grasp a handle and perform a certain exercise ormovement. Then, at a desired point or points during the motion, aperturbation is delivered in less than 500 ms to the joint involved inthe exercise for recordal of results for subsequent training purposes.

This unique apparatus can be employed to carry out the new and novelmethod of disturbance event training of the present invention, whichincludes fall prevention and other joint movement training.

For the fall prevention training aspect of the present invention, it ispreferred that the following steps are provided as part of a uniqueprotocol, however, less than all of the steps may be employed and stillbe within the scope of the present invention. Using the platform of thepresent invention, from a stop, a sequence of disturbance events areproduced with incrementally increasing perturbation distance thatestablishes a first threshold of that individual's “foot in place”response and not a step response.

Next, from a stop, a sequence of disturbance events are produced withincrementally increasing perturbation distance that establishes a secondthreshold beyond which the individual can not execute a single stepresponse.

Next, a first obstacle, having a first obstacle height, is placedproximate to the platform at a first obstacle distance to induce thestep response of the individual to the disturbance event. From a stop, asequence of disturbance events are produced with incrementallyincreasing perturbation distance that establishes a third thresholdbeyond which the individual can not execute a single step response whileattempting to negotiate the obstacle. Further, from a stop, a sequenceof the combination of a disturbance event with incrementally increasingperturbation distance are produced followed by a continuous platformmotion simulating walking velocity that establishes a fourth thresholdbeyond which the individual can not achieve a stable gait response.

Next, from a stop, a stable gait response is sought from the individual.If they are able to achieve a stable gait within a predetermined numberof steps, the trial is considered successful. If the individual requiresmore than the predetermined number of steps to achieve stable gait or ifthe individual falls, the change in velocity is repeated. Trials are berepeated within a session or across sessions until the variability instep response following a given perturbation displacement and profileare below a target value.

Next, a second obstacle, having a second obstacle height, is placedproximate to the platform at a second obstacle distance to induce thestep response of the individual to the disturbance event. From a stop, asequence of a combination of a disturbance event with incrementallyincreasing perturbation distance is produced followed by a continuousplatform motion simulating walking velocity that establishes a fifththreshold beyond which the individual can not achieve a stable gaitresponse. Further, from a first walking velocity created by a continuousplatform motion, a sequence of the combination of a disturbance eventwith incrementally increasing perturbation distance is produced followedby a continuous platform motion returning to the first walking velocitythat establishes a sixth threshold beyond which the individual can notachieve a stable gait response.

Next, the individual starts at an initial steady state locomotionvelocity with a large disturbance introduced at a random time. Thedisturbance causes the platform to accelerate to a prescribeddisturbance velocity before returning to a second steady statelocomotion velocity. The maximum time for this change in the platformvelocity is less than about 500 ms, and is more typically in the rangeof about 100 to about 200 ms. A stable gait response is sought from theindividual.

Finally, a third obstacle, having a third obstacle height, is placedproximate to the platform at a third obstacle distance to induce thestep response of the individual to the disturbance event. From a secondwalking velocity created by a continuous platform motion, a sequence ofthe combination of a disturbance event with incrementally increasingperturbation distance is produced followed by a continuous platformmotion returning to the second walking velocity that establishes aseventh threshold beyond which the individual can not achieve a stablegait response.

It is therefore an object of the present invention to provide a new andnovel apparatus for use with fall prevention training that moreaccurately simulates a disturbance event, such as a slip or tripincident, more closely than prior art apparatus.

It is another object of the present invention to provide an apparatusand system that can measure the biomechanics of a disturbance event tofurther assist a person to better respond to the incident to avoid afall.

Another object of the invention is to provide an apparatus that iswell-suited to measure such biomechanics.

An object of the invention is to provide an apparatus that can simulatevarious disturbance events that could lead to a fall so an appropriateresponse can be developed.

A further object of the present invention is to provide a new and novelmethod for fall prevention training that train a person to avoid a fallwhen encountered with a disturbance event.

Another object of the present invention is to provide a method for fallprevention training that better prepares an individual for a disturbanceevent to avoid injury or death.

Yet another object of the present invention is to provide a method forfall prevention training that has a protocol that effectively trains theindividual while isolating the weaknesses of the individual.

An object of the current invention is to provide task-specific,neuromuscular, dynamic perturbation training to prevent injury to theanterior cruciate ligament (ACL) and other soft tissues in the joints ofthe lower limb and to improve outcomes for athletes who sustain theseinjuries, either with or without subsequent surgery to repair or replacethe injured ligament or ligaments. Previous research has demonstratedthat manual perturbation training has been shown to improve outcomes forboth ACL-deficient (ACL-D) and ACL-reconstructed (ACL-R) populationscompared to the strength training alone.

An object of the current invention is to provide perturbations thatinduce joint instability that requires a neuromuscular response toretain and maintain balance, joint stability, and joint response time todisturbances The joint instability can occur at a single joint,simultaneously at multiple joints throughout the body, or attime-delayed periods at different joints. The instability requires aresponse, such as a step response or other, anything from the movementof one or more joints to actually physically changing the body's base ofsupport (moving the foot or feet) to maintain balance. The joint(s)affected by the perturbation are a function of the timing in the gaitcycle, the body position and body motion (e.g. defined as the motion ofthe center of mass, or the motion of independent limbs, and the like) atthe time of the perturbation, and the magnitude of the perturbationdelivered. Any joint in the body can be affected by this.

An object of the current invention is to provide perturbations thatinduce joint instability that requires a neuromuscular response toretain and maintain balance, joint stability, and joint response time todisturbances The joint instability can occur at a single joint,simultaneously at multiple joints throughout the body, or attime-delayed periods at different joints. The instability requires aresponse, such as a step response or other, anything from the movementof one or more joints to actually physically changing the body's base ofsupport (moving the foot or feet) to maintain balance. The joint(s)affected by the perturbation are a function of the timing in the gaitcycle, the body position and body motion (e.g. defined as the motion ofthe center of mass, or the motion of independent limbs, and the like) atthe time of the perturbation, and the magnitude of the perturbationdelivered. Any joint in the body can be affected by this. Perturbationscan be delivered to any joint in the body, whether or not it is in thelower or upper extremity of the body and whether or not the joint isassociated with the act of walking.

Another object of the current invention is to provide task-specific,neuromuscular, dynamic perturbation training to prevent the developmentand progression of osteoarthritis.

Another object of the current invention is to provide perturbations,such as those that are continuous or periodic or aperiodic, during thedifferent phases of stance of the gait cycle.

Another object of the current invention is to provide perturbations,such as those that are continuous or periodic or aperiodic, during eachstance phase of the gait cycle.

Another object of the current invention is to provide modulation of thestretch reflex to prevent ankle sprains.

Another object of the current invention is to provide perturbationsduring the athlete training or physical therapy where the perturbationsare delivered automatically without any manual intervention from anotherindividual or medical provider.

Another object of the current invention is to provide perturbationsduring the stance phase of the gait cycle that are synchronized withmusical cues or other external stimuli, including but not limited tovisual, auditory and tactile stimuli.

A further object of the present invention is to provide perturbations toany joint of the body to help prevent disease and injury thereto.

Another object of the current invention is to provide perturbations ofvarying magnitude, direction and duration that are generatedautomatically based on the timing of music driving the system. Anotherobject of the current invention is to provide selection of music orother external cues to be presented to a user based on the perturbationprofile selected for a given neuromuscular training activity

Another object of the current invention is to provide perturbations thatare based on the timing of braking and propulsions of a joint.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features which are characteristic of the present invention areset forth in the appended claims. However, the invention's preferredembodiments, together with further objects and attendant advantages,will be best understood by reference to the following detaileddescription taken in connection with the accompanying drawings in which:

FIG. 1 is a perspective view of the apparatus of the present invention;

FIG. 2 is a close-up perspective view of the apparatus of the presentinvention equipped with a physical obstacle;

FIG. 3 is a close-up perspective view of the apparatus of the presentinvention equipped with a virtual obstacle in the form of a laser beam;

FIG. 4 is a close-up perspective view of the apparatus of the presentinvention equipped with a virtual obstacle in the form of a hologram;

FIG. 5 is a top plan view of an inertial sensor used in the presentinvention;

FIG. 6 is a graph showing speed against time for executing a standingand walking perturbation in accordance with the present invention;

FIG. 7 is a graph showing the increase in recovery percentage inindividuals over time as a result of fall prevention training;

FIG. 8 is a flow chart illustrating the execution of Stage 1 of themethod of the present invention;

FIG. 9 is a flow chart illustrating the execution of Stage 2 of themethod of the present invention;

FIG. 10 is a flow chart illustrating the execution of Stage 3 of themethod of the present invention;

FIG. 11 is a flow chart illustrating the execution of Stage 4 of themethod of the present invention;

FIG. 12 is a flow chart illustrating the execution of Stage 5 of themethod of the present invention;

FIG. 13 is a flow chart illustrating the execution of Stage 6 of themethod of the present invention;

FIG. 14 is a flow chart illustrating the execution of Stage 7 of themethod of the present invention;

FIG. 15A is an exploded front view of a lateral deck to provide lateralperturbations controlled by a DC rack-and-pinion drive centered underthe deck and slides on a low friction polymer surface that is fixed toan aluminum sub-frame;

FIG. 15B is perspective view of a lateral deck shown in FIG. 15A withthe sub-frame;

FIG. 15C is a perspective view of a motor transmission that is inlinewith the MR clutch and drive roller;

FIG. 16 is a graphical representation of an algorithm according to thepresent invention that performs real-time event (e.g. heelstrike ortoe-off) detection based on motor current;

FIG. 17 is a flowchart illustrating a process for detecting gait phase,such as heel strike and toe off, in accordance with the presentinvention;

FIGS. 18A-F illustrate various graphs of data collected for a one stepcycle in accordance with the gait phase detection process in accordancewith the present invention;

FIGS. 19A-D illustrate various graphs of multi-step data relating tooperation of the motor of a perturbation platform in accordance with thepresent invention;

FIG. 20 is a flowchart illustrating the interrelation of the componentsused for delivering and controlling perturbations in accordance with thepresent invention;

FIG. 21 illustrates the effects of delivering perturbations forces atdifferent phases of the gait cycle such as heelstrike and midstance,resulting in different kinetic and kinematic responses.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention includes a unique method that enables individuals,particularly older adults, to rapidly learn how to modify motorperformance and improve recovery rates after being subjected to adisturbance event or perturbation that required a response, such as astep response. The method of the present invention achieves a reductionin the probably of falling by repeated exposure to a realisticdisturbance event which serves as targeted and effective motor skilltraining. As seen in FIG. 7, the recovery percentage increasesexponentially over time when they are subjected to trials of fallprevention training. Thus, the method of the present invention providesan invaluable rehabilitation tool for an individual for training how torecover from a large disturbance event, such as a large posturalperturbation. To carry out this method, the present invention employs acost-effective apparatus that can be widely used to reduce the incidenceof falling.

The present invention includes a new and novel apparatus and a methodwhich can use that apparatus for fall prevention training. It should beunderstood that it is preferred that the apparatus of the presentinvention be used to carry out the method of the present invention.However, the method of the present invention can be carried out by amany different types of training apparatus and still be within the scopeof the present invention. The preferred embodiment of the apparatus inaccordance with the present invention is set forth in detail below inconnection with FIGS. 1-6.

Referring first to FIG. 1, an apparatus 10 for use in carrying out themethod of the present invention is provided. Preferably, the apparatus10 is in the form of a force-treadmill perturbation treadmill 12, asshown in FIG. 1, for use in identifying individual risk factors forfalling in an individual 14. The following details of the apparatus 10are preferred to carry out the method. However, it should be understoodthat many other different types of apparatus 10 can be employed and thecomponents therein can be modified to suit the application at hand. Allof these modifications are deemed to be within the scope of the presentinvention.

The treadmill 12 includes a left belt 16 and a right belt 18, which areboth preferably bi-directional for maximum control and timing of beltposition, velocity and acceleration. For example, each belt 16, 18preferably has bi-directional displacement control for largeperturbations from 6 mm (0.25 in) to infinity (continuous operation)with minimum 6 mm (0.25 in) resolution. The belts 16, 18 also havebi-directional velocity control from 0-4 m/s (˜9 mph) and bi-directionalacceleration control from 0-6 m/s². The belts 16, 18 are criticallytuned to avoid oscillations. As far as preferred dimensions, each belt16, 18 is approximately 250 mm (˜10 in) wide with a platform length ofapproximately 1.6 m (5 ft). It is also possible that a single belt (notshown) may be used instead of the dual belts 16, 18 shown in FIG. 1.

The apparatus 10 also includes a motor and drive system 20. A hightorque direct drive motor is preferred although other drive systems 20may be used. Motors for driving belts are well known in the art and neednot be discussed further therein.

Most importantly, the apparatus 10 is configured to create thedisturbance event in less than 500 ms. More preferably, the disturbanceevent is created in the range of about 100 to about 200 ms. The creationof the disturbance event, such a movement of a belt 16 or 18, at such afast speed is not found in the prior art. The relatively short durationof the disturbance event is used so that it simulates a real disturbanceevent to trigger a more accurate response from the individual 14.

FIG. 6 is a graph of the speed of a belt 16, 18 against time toillustrate the unique fast creation of a disturbance event. Line 62represents the speed of creation of a disturbance event for a standingperturbation where the individual 14 is standing still and belts 16, 18are ramped up to a 2 MPH speed in the range of about 100 to about 200ms. Similarly, line 64 Line 64 represents the speed of creation of adisturbance event for a walking perturbation where the individual 14 iswalking at about 2 MPH and belts 16, 18 are accelerated over 4 MPH inthe range of about 100 to about 200 ms.

Further, multi-axis load transducers 22, such as low-profile multi-axisload cells with desired range, accuracy, and sensitivity, which supportthe platform, generally referred to as 24 of treadmill 12, and drums 26of the treadmill apparatus 12. The pressure applied by an individual 14to the bed of the platform 24 can be measured with such pressuretransducers 22.

The apparatus 10 of the present invention also includes a number ofsensors 28 that are attached the individual 14 that is being trained andoptionally at various locations on the apparatus 10 itself. For example,inertial sensors 28, which are well known in the art, can be placed onvarious parts of the body of the individual 14 to sense position andvelocity. An example of a prior art inertial sensor 28 is shown in FIG.5 with circuit board 29 and electrical lead 31. As a further example, aninertial sensor 28 can be positioned on the trunk of the individual 14to sense trunk angle and velocity, which are important factors to bestudied in connection with fall prevention training. While sensors 28are preferred, other ways to measure body location can be used, such asvideo analysis of body movement.

Sensors located between the underside of the belts and the deck of theapparatus sense the location of the subject's foot as it contacts theplatform. This plurality of sensors is preferably in an array with asensing element every 1 cm in both the length and width direction of theapparatus. In the preferred embodiment, these sensing elements are made,for example, from a thin pressure sensitive material and are contactsensors whose electrical output is triggered when foot contact pressureto the sensor through the belt exceeds a certain pre-determined level.While this array of thin contact sensing elements is the preferredembodiment, these sensing elements could also produce a voltage whoseoutput was proportional to applied pressure or force. Also, while thinpressure sensitive material is preferred, any type of sensors, which canbe either of the digital ON/OFF or proportional analog, can also be usedin accordance with the present invention.

The sensors 28 gather data regarding the various parameters that arebeing monitored. This data is, preferably in real-time, sent to acomputer 30 for processing and analysis. The data may be sent to thecomputer 30 wirelessly or by hard wire. Data transmission and computerprocessing devices are so well known in the art that they need not bediscussed in further detail herein.

The apparatus 10 itself preferably includes its own central control unit32 with the appropriate control algorithm and custom motor controlsoftware, which provides bilateral, independent bi-directional real-timebiofeedback motor control function. The control algorithm is written asa state machine, and responds according to a lookup-table of inputs todetermine the next step. A radio frequency (RF) telemetry console 34 isused for many operational functions of the apparatus 10, includingprogramming and operation of handrails 36, safety harness 38, andemergency stop switch 40. The control algorithm is preferably written inC using LabWindows CVI software and, where appropriate, nativemicrocontroller firmware language. The key elements of the controlsystem 32 include encoders attached to drive motors provide data formotion control of the platform 24 and PID algorithms for smooth,accurate motion. Also, the control system handles triggering ofperturbations at specific times during the walking cycle based on forcemeasurements and monitoring and recording of step recovery response andappropriate state-machine response to inputs. There are also safetyinterlocks to protect the individual 14. Thus, the treadmill apparatus10 of the present invention includes two main components, theperturbation platform (PPU) 24 with force measurement capability, safetyharness 38 and handrails 36 as well as a central control unit (CCU) 32with control algorithms, safety interlocks, data storage and transferprotocols, and user interface.

Referring back to FIG. 1, the treadmill apparatus 10 includes a frame 42to integrate the platforms on the underside of each transducer andprovide rigid attachment points for the mounting of the treadmill 10 tothe ground. The frame 42 is designed to minimize any mechanicalcrosstalk that may be induced by the use of a common frame. The belts16, 18 and platforms 44 thereunder are separated by a physical width of0.125 in. to minimize any influence two separate belts 16, 18 may haveon gait patterns of the individual 14 during walking while preventingany belt overlap that may occur.

The apparatus 10, which includes a motor controller and amplifier withassociated electronics within the CCU 32, is preferably PC based withcabling to the amplifiers to enable a development environment fortesting.

The apparatus 10, as seen in FIG. 1, also includes a harness system 38that embraces the individual 14 and is suspended from support bar 48 viatether 50. Support bar 48 is positioned by vertical posts 54. Forcetransducers 46, mounted in the training harness 38, generate use inputsignals to determine when an individual 14 has fallen. The harness 38 isused as both a safety subsystem and as a control input device to systemsoftware, and is integrally attached to the platform 24 through thesubsystem frame. Known chest harnesses (e.g. climbing chest harness) areintegrated to the subsystem frame using tubular steel. Further,low-profile handrails 36 are included as a safety feature. The handrails36 are attached to the treadmill 12 base in such a way that the forcetransducers 52 can identify and quantify when the rails 36 are beingused to support the individual's body weight. This data is also used forreal-time biofeedback control of the treadmill 12. Powder coated benttubular steel and powder coated for each rail 36, 54 is preferredalthough other handrail constructions may be used.

Software modules are an important component of the apparatus and controlthereof of the present invention. Software modules are preferablydeveloped in a high level language, such a C, but are designed forimplementation on an embedded microcontroller or dedicatedmicroprocessor. Computational modules are also employed for kinematicmeasurements derived from numerous markers placed on the body forcomputations of stepping response to large postural perturbations. Forexample, 26 markers on the body of the individual 14 may be used. Thesemeasures, including trunk angle and trunk velocity, are of assistance todiscriminate fallers versus non-fallers.

It should be understood that each of the foregoing components arepreferably included in the apparatus 10 of the present invention.However some components and features may be omitted from the apparatusand still be within the scope of the present invention. For example, theapparatus 10 employs force transducers 44, 46, 54, however, such forcemeasurements may not be required for the analysis of the kinetic data inorder to be effective as a training tool. For example, it may besufficient to have programmed control algorithms and relatively simplesensing capabilities that perform universal protocols.

Referring now to FIGS. 2-4, the optional use of obstacles with theapparatus 10 of the present invention. The use of such obstacles in themethod of training of the present invention improves the overalleffectiveness thereof. In FIG. 2, the treadmill 24 is equipped with aphysical obstacle 56 that is placed proximate to the individual. Forexample, the obstacle 56 is a wall or barrier that is place in front ofthe walking path of the individual 14. This obstacle 56 may be placeabove the belts 16, 18 or may be placed directly thereon. Or, theobstacle 56 may, upon command, emanate upwardly from the platform 24 tothen be proximate to the individual 14.

In FIG. 3, the obstacle employed, in this embodiment, is a laser beam 58that passes proximate to the individual 14, namely, in their walkingpath. Still further, in FIG. 4, the obstacle employed, in thisembodiment, is a hologram 60. As will be discussed below, in connectionwith the method of the present invention, the obstacles 56, 58 and 60play an important role in training the individual 14. The obstacles 56,58 and 60 simulate real obstacles that may be faced in a real worldnon-training setting. The virtual obstacles 58 and 60 may also be usedto sense when the individual 14 passes therethrough to serve as anadditional sensor.

In view of the foregoing, the apparatus 10 of the present invention canmeasure an individual's step response to a disturbance event, such astrip or slip incident. Therefore, it can be used to evaluate trippingand slipping fall mechanism in anterior and posterior directions. It canalso evaluate stepping responses from static positions in the anterior,posterior and lateral directions. Recovery strategies can also beevaluated to reduce occurrences of falls. The complete measurement andcomputational capabilities of the present invention enables specificindividual risk factors to be identified so appropriate training can bedeveloped and carried out to better avoid fall incidents. Thus, novelbiomechanical factors can be linked to the prediction and prevention offalling with better accuracy and effectiveness than prior art devicesand systems.

The data obtained from the system and apparatus of the present inventioncan then be used to better train a person for a fall in accordance withthe new method for fall prevention training of the present invention. Asdiscussed in detail below, the apparatus 10 can be used to execute aunique protocol of fall prevention training that teaches a person how tobetter react to a disturbance event according to strategies learned fromthe apparatus and system described above. For example, a succession ofsimulated trip incidents can be delivered where the velocities and/oraccelerations or a combination thereof of each successive event is builtup over time to lead up to a trip situation. By using the uniqueapparatus 10 of the present invention, a method of training can bedelivered where a slip incident can be generated from a static position.This simulates a condition where an individual loses their balance whenstanding still.

Also, and most importantly, the present invention can generate a dynamicslip or trip condition where a second velocity is delivery after a firstvelocity has been delivered. This simulates a condition where theindividual is walking (corresponding to the first velocity) and thenencounters a trip or slip situation while walking. Thus, a change ofvelocities can be delivered to better simulate various conditions thatcannot be simulated with prior art devices. Such a method of training ispreferably carried out using the apparatus of the present inventiondescribed above.

Referring now to FIGS. 8-14, details of the method of fall preventiontraining is shown and described in detail. The method of the presentinvention provides a protocol to execute and carry out the fallprevention training of the present invention. This is a general protocolemployed in the method of the present invention and can be applied toany of the large disturbance events used in the present method oftraining. As will be discussed in detail below, the method is amulti-stage process that outlines a unique training progression that isused in an attempt to reduce the incidence of falls by an individual.While this is a preferred method, there is no set number of cycles orlimits. In general, the method uses a unique protocol that requires theindividual to achieve a goal to represent the acquisition of a givenskill. Moreover, multiple trials at a given disturbance level representsskill retention and the results of future retesting indicates skilldecay.

Stage 1—Small Disturbance, No Step Response

As represented by FIG. 8, in the first stage of the protocol, theindividual 14 stands with two feet on platform. A small disturbance isintroduced at a random time. The platform moves a finite distance andstops. As stated above, the platform moves in less than about 500 msand, preferably, in the range of about 100 ms to about 200 ms to ensurea realistic disturbance event. The disturbance level in Stage 1 shouldbe small to determine if the individual can use respond to thedisturbance with what is commonly referred to as a “feet in place”recovery strategy. This means that the individual adopts a recoverystrategy that maintains upright posture and which requires minimalmovement of the feet (e.g. no step response).

For example, the individual might use what is referred to as an “anklestrategy” or a “hip strategy” whereby the individual alters their ankleand/or hip rotation angle in one or more directions and stabilizes theirbody with their muscles with no step response. At this stage, theperturbation distance preferably remains the same until the individualhas shown that their response is low in variability.

The perturbation distance incrementally increases at 64 as theindividual successfully completes the feet in-place response. Thisincrease in distance continues until the individual is able to completea prescribed distance, or threshold, which is determined based onintrinsic parameters of the individual, such as height, body center ofmass, age, and flexibility. Once the individual has exceeded thepredetermined maximum perturbation threshold without a step response at66, the sequence of disturbance events are stopped at 68 and they aremoved to the Stage 2 in the protocol at 70.

Stage 2—Step Response to Large Perturbation

In FIG. 9, the individual starts at a standstill and a large disturbanceis introduced at a random time. The platform moves a finite distance andstops. The disturbance magnitude preferably exceeds the magnitude of themaximum disturbance in Stage 1 above. The maximum time for thisdisplacement of the disturbance to occur is less than 500 ms, and ismore typically in the range of about 100 to about 200 ms, and preferablyabout 250 ms.

In Stage 2, a single step response by the individual is sought. If theindividual is able to maintain posture with a single step, the giventrain within Stage 2 is considered successful. If the individualrequires more than one step to maintain posture or falls, theperturbation distance is repeated.

Trials are be repeated within a session or across sessions until thevariability in step response following a given perturbation displacementand profile are below a target value. For example, a minimizationfunction relating step length and step width might be employed tocalculate a residual value for step response. This value is called atarget step response. The variance in this computed value for a giventrial compared to the previous n trials can be used. Alternative methodsof determining a threshold for success for step response to a givenperturbation are readily defined, such as the number of trials in a rowfor achieving the target step response required by Stage 2.

After an individual successfully passes the single step response testfor a given perturbation distance and acceptably low variability betweensessions, that distance is increased at 72 until individual is able tocomplete a prescribed perturbation distance threshold at 74. In similarfashion to Stage 1, intrinsic parameters of the individual, such asheight, body center of mass, age, and flexibility, are used to determinea maximum perturbation distance, or threshold, for that individual. Oncethe individual has exceeded the predetermined maximum perturbation withonly a single step response, the sequence of disturbance events arestopped at 76 and they are moved to the Stage 3 in the protocol of themethod of the present invention at 78.

Stage 3—Step Response with First Obstacle

In FIG. 10, the individual starts at a standstill. A first obstacle isplaced proximate to the individual at 80, such as ahead of theindividual in the direction, so that the perturbation forces them tomake a step response. A large disturbance is also introduced at a randomtime. The platform moves a finite distance and stops. The disturbancemagnitude exceeds the magnitude of the maximum disturbance in Stage 1.The maximum time for this displacement of the disturbance to occur isless than about 500 ms, and is more typically in the range of about 100to about 200 ms.

The distance and position that the first obstacle is placed from theindividual can vary between zero (i.e. touching the individual) and aprescribed maximum obstacle distance from individual. Intrinsicindividual parameters, such as height and body center of mass, are usedto determine a maximum obstacle distance from individual for thatindividual. The obstacle can either be real or virtual. For example, theobstacle, which may be made from any material, may be a barrier or wallthat emanates up from the floor of the platform. Such an obstacle may bedriven by springs or actuators to control its positioning proximate tothe individual. For virtual obstacles, 3-D holograms and laser beamsystems are a few examples. In the preferred embodiment of the presentinvention, the obstacle is 5 cm high but it could be of any height. Forexample, the obstacle may be in the range of only about 1 mm up to aboutone half of the body height of the individual.

A single step response is sought from the individual. If they are ableto negotiate the obstacle and to maintain posture with a single step,the trial is considered successful. If the individual requires more thanone step to maintain posture or falls, the perturbation distance isrepeated.

Trials are repeated within a session or across sessions until thevariability in step response following a given perturbation displacementand profile are below a target value. For example, a minimizationfunction relating step length and step width might be employed tocalculate a residual value for step response. This value is called atarget step response. The variance in this computed value for a giventrial are compared to the previous n trials can be used. Alternativemethods of determining a threshold for success for step response at 84to a given perturbation are readily defined, such as the number oftrials in a row for achieving the target step response.

After a individual successfully passes the single step response test fora given perturbation distance, that distance is incrementally increasedat 82 until individual is able to complete a prescribed distance. Also,the height of the obstacle is progressively increased at 83 up to aprescribed height and the initial distance of the obstacle from theindividual is progressively increased up to a prescribed perturbationdistance.

The intrinsic individual parameters, such as height, body center ofmass, age, and flexibility, are used to determine a maximum perturbationdistance for that individual, the maximum obstacle height for thatindividual and the maximum initial obstacle distance for the individual.Once the individual has exceeded the predetermined maximum perturbation,with only a single step response and acceptably low variability betweensessions, the disturbance events are stopped at 86 and they are moved tothe Stage 4 at 88 in the protocol outlined below. It should be notedthat in the case where the disturbance event is intended to be large andto simulate a slip incident, Stage 3 may be omitted.

Stage 4—Stable Gait after Standstill

In FIG. 11, the individual 14 starts at a standstill and a largedisturbance is introduced at a random time. The disturbance causes theplatform to accelerate to a prescribed (non-zero) velocity. This secondvelocity is called the velocity change. The maximum time for this changein the platform velocity is less than about 500 ms, and is moretypically in the range of about 100 to about 200 ms.

A stable gait response is sought from the individual. If they are ableto achieve a stable gait within a predetermined number of steps, thetrial is considered successful. If the individual requires more than thepredetermined number of steps to achieve stable gait or if theindividual falls, the change in velocity is repeated. Trials are berepeated within a session or across sessions until the variability instep response following a given perturbation displacement and profileare below a target value.

For example, a minimization function relating step length and step widthmight be employed to calculate a residual value for step response. Thisvalue is called a target step response. The variance in this computedvalue for a given trial compared to the previous n trials can be used.Alternative methods of determining a threshold for success for stepresponse to a given perturbation are readily defined, such as the numberof trials in a row for achieving the target step response.

After a individual successfully passes the stable gait response test fora given velocity change perturbation, that velocity change isincrementally increased at 90 to produce continuous walking at 92 untilindividual is able to successfully complete a prescribed velocitychange. Intrinsic individual parameters, such as height, body center ofmass, age, and flexibility, are used to determine a maximum velocitychange threshold at 94 for that individual. Once the individual hasexceeded the predetermined maximum velocity change with stable gait stepresponse and acceptably low variability between sessions, thedisturbance events are stopped at 96 and they are moved to the Stage 5in the protocol at 98.

Stage 5—Stable Gait after Standstill with Second Obstacle

In FIG. 12, the individual 14 starts at a standstill. A second obstacleis placed proximate to the individual at 100, such as ahead, in thedirection such that the perturbation forces them to make a stepresponse. This second obstacle may be the same as the first obstacle butalso may be a different obstacle. A large disturbance is introduced at arandom time. The disturbance causes the platform to accelerate to aprescribed (non-zero) velocity. This second velocity is called thevelocity change. The maximum time for this change in the platformvelocity is less than 500 ms, and is more typically in the range ofabout 100 to about 200 ms.

The distance that the second obstacle is placed from the individual canvary between zero (i.e. touching the individual) and a prescribedmaximum obstacle distance from individual. Intrinsic individualparameters, such as height, body center of mass, age, and flexibilityare used to determine a maximum obstacle distance or threshold fromindividual for that individual. As above, the second obstacle can eitherbe real virtual and preferably 5 cm high, although, the obstacle couldbe in the range of 1 mm up to about one half of the body height of theindividual.

A stable gait response is sought in Stage 5. If the individual is ableto achieve a stable gait within the predetermined number of steps, thetrial is considered successful. If the individual requires more than thepredetermined number of steps to achieve stable gait or if theindividual falls, the change in velocity is repeated.

Trials are be repeated within a session or across sessions until thevariability in step response following a given perturbation displacementand profile are below a target or threshold value. For example, aminimization function relating step length and step width may beemployed to calculate a residual value for step response. This value isbe called a target step response. The variance in this computed valuefor a given trial compared to the previous n trials can be used.Alternative methods of determining a threshold for success for stepresponse to a given perturbation are readily defined, such as the numberof trials in a row for achieving the target step response.

After a individual successfully passes the stable gait response test fora given velocity change perturbation, that velocity change is increaseduntil individual is able to successfully complete a prescribed velocitychange at 108. The height of the obstacle is progressively incrementallyincreased up to a prescribed height at 106. The initial distance of thesecond obstacle from the individual is progressively incrementallyincreased at 102 up to a prescribed distance. Intrinsic individualparameters, such as height, body center of mass, age, and flexibility,are used to determine, for that individual, the maximum velocity change,the maximum obstacle height and the maximum initial obstacle distancefor that individual. Once the individual has exceeded the predeterminedmaximum velocity change with stable gait step response at 108 andacceptably low variability between sessions, the disturbance events arestopped at 110 and they are moved to Stage 6 in the protocol at 112 ofthe method of the present invention. It should also be noted that in thecase where the disturbance event is large and is intended to be a slipincident, Stage 5 may be omitted.

Stage 6—Stable Gait after Initial Steady State Locomotion and LargeDisturbance

In FIG. 13, the individual starts at an initial steady state locomotionvelocity (velocity 1). A large disturbance is introduced at a randomtime. The disturbance causes the platform to accelerate to a prescribeddisturbance velocity (velocity 2) before returning to a second steadystate locomotion velocity (velocity 3). The maximum time for this changein the platform velocity (the time between when the change from velocity1 is initiated and velocity 3 is achieved) is less than about 500 ms,and is more typically in the range of about 100 to about 200 ms.Velocity 3 may or may not be different from velocity 1. The threevelocities and their timing are called the velocity profile.

A stable gait response is sought from the individual. If they are ableto achieve a stable gait within a predetermined number of steps, thetrial is considered successful. If the individual requires more than thepredetermined number steps to achieve stable gait or if the individualfalls, the velocity profile is repeated.

Trials are be repeated within a session or across sessions until thevariability in step response following a given perturbation displacementand profile are below a target value or threshold. For example, aminimization function relating step length and step width may beemployed to calculate a residual value for step response. This value isbe called a target step response. The variance in this computed valuefor a given trial compared to the previous n trials can be used.Alternative methods of determining a threshold for success for stepresponse to a given perturbation are readily defined, such as the numberof trials in a row for achieving the target step response.

After a individual successfully passes the stable gait response test fora given velocity profile perturbation, parameters in that velocityprofile are incrementally increased until individual is able tosuccessfully complete a prescribed velocity profile. For example, themagnitude of the disturbance (defined as the difference between velocity1 and velocity 2) is progressively and incrementally increased up at 114to a prescribed disturbance magnitude, velocity 1 is progressively andincrementally increased up to a prescribed velocity and velocity 3 isincrementally increased up to a prescribed velocity to achieve motion tosimulate walking at 116.

Intrinsic individual parameters, such as height, body center of mass,age, and flexibility, are used to determine the final velocity profilefor that individual. Once the individual has exceeded the predeterminedfinal velocity profile with stable gait step response at 118, thedisturbance events are stopped at 120 and they are moved to Stage 7 inthe protocol of the method of the present invention.

Stage 7—Stable Gait after Initial Steady State Locomotion and LargeDisturbance with Third Obstacle

In FIG. 14, the individual 14 starts at an initial steady statelocomotion velocity (velocity 1). A large disturbance is introduced at arandom time. In concert with the large disturbance, a third obstacle isplaced proximate to the individual at 124, such as ahead of theindividual, in the direction so that the perturbation forces them tomake a step response. The third obstacle may be the same as the firstobstacle and/or the second obstacle. Alternatively, all three obstaclesmay be different than one another. The disturbance causes the platformto accelerate to a prescribed disturbance velocity (velocity 2) beforereturning to a second steady state locomotion velocity (velocity 3). Themaximum time for this change in the platform velocity (the time betweenwhen the change from velocity 1 is initiated and velocity 3 is achieved)is less than about 500 ms, and is more typically in the range of about100 to about 200 ms. Velocity 3 may or may not be different fromvelocity 1. The three velocities and their timing are called thevelocity profile.

The distance that the third obstacle is initially placed from theindividual can vary between zero (i.e. touching the individual) and aprescribed maximum obstacle distance from individual. Intrinsicindividual parameters, such as height, body center of mass, age, andflexibility are used to determine a maximum obstacle distance from theindividual for that individual. Similar to the first obstacle and thesecond obstacle, the third obstacle can either be real or virtual. Inthe preferred embodiment of the present invention, the third obstacle isabout 5 cm high but it can be in the range of about 1 mm up to about onehalf of the body height of the individual.

A stable gait response is sought from the individual. If the individualis able to achieve a stable gait within a predetermined number of steps,the trial is considered successful. If the individual requires more thanthe predetermined number of steps to achieve stable gait or if theindividual falls, the velocity profile is repeated.

Trials are be repeated within a session or across sessions until thevariability in step response following a given perturbation displacementand profile are below a target value. For example, a minimizationfunction relating step length and step width may be employed tocalculate a residual value for step response. This value is called atarget step response. The variance in this computed value for a giventrial compared to the previous n trials can be used. Alternative methodsof determining a threshold for success for step response to a givenperturbation are readily defined, such as the number of trials in a rowfor achieving the target step response.

After a individual successfully passes the stable gait response test fora given velocity profile perturbation, parameters in that velocityprofile are incrementally increased until the individual is able tosuccessfully complete a prescribed velocity profile. For example, themagnitude of the disturbance (defined as the difference between velocity1 and velocity 2) is incrementally increased at 126 up to a prescribeddisturbance magnitude to produce a motion simulating a walking velocityat 128. Velocity 1 is incrementally increased up to a prescribedvelocity and velocity 3 is incrementally increased up to a prescribedvelocity. The height of the third obstacle is progressively increased upto a prescribed height at 130 and the initial distance of the thirdobstacle from the individual is progressively increased up to aprescribed distance.

Intrinsic individual parameters, such as height, body center of mass,age, and flexibility, are used to determine the final velocity profile(including maximum velocity 1, maximum velocity 2, and maximum magnitudeof disturbance), maximum obstacle height, maximum initial obstacledistance for that individual. Once the individual has exceeded thepredetermined final velocity profile with stable gait step response at132 and acceptably low variability between sessions, the disturbanceevents are stopped at 134 and protocol of the method of the presentinvention is completed at 136. It should also be noted that in the casewhere the disturbance event is large and is intended to be a slipincident, Stage 7 may be omitted.

Referring now to FIGS. 15A, 15B, 15C and 20, a lateral deck 200 of thepresent invention is controlled by a DC rack-and-pinion drive 202, withcenter under deck, that slides on a low friction polymer surface 204that is fixed to an aluminum sub-frame 206. The drive motor 208 androllers 210 are all mounted on the deck 200 to maintain alignment of thewalkway belt via drive pulleys 211. A locking mechanism prevents lateralmotion when desired. At a specific phase of the gait cycle, the lateralmechanism moves the entire deck assembly 200 relative to the sub-frame206 using the DC rack-and-pinion drive at a specified velocity anddistance delivering a lateral perturbation to the user. The lateral deck200 of FIGS. 15A, 15B and 15C is a further embodiment of the presentinvention compared to the deck shown in FIG. 1.

To the end user, the system resembles a treadmill and has similarfunctionality as a traditional treadmill, but with the added highlycontrolled perturbations that are superimposed with treadmill velocityat, for example, specific phases in the gait cycle or from externaltriggers, to elicit a targeted user response. Perturbations are highacceleration changes in gait velocity that last less than 500 msec andpreferably less than 150 ms.

In one embodiment of the present invention, referring to FIGS. 15A, 15Band 15C and representationally shown in FIG. 20, a novel roller/brakeclutch system 220, alternatively referred to as a slip clutch system,such as a electromagnetic (EM) or magnetorheological (MR) roller/brakeclutch, connected between drive pulley 213 and drive roller 210 isadapted to existing AC motors currently used in commercial treadmills toprovide a microprocessor controlled mechanism for precise control ofperturbation displacement, velocity, and acceleration. For example, aroller/break clutch 220 controls the slip characteristics at the desiredtiming for the perturbation. In this embodiment, the perturbations areachieved by utilizing the horizontal reaction force generated duringstance to overpower the low-inertia rollers 210 and coupled slip clutchsystem 220 in FIG. 15C.

It should be understood that alternate embodiments for creating thedesired perturbation kinematics exist. The equipment shown and discussedherein are examples of how the method of the present invention can becarried out.

In a preferred embodiment of the present invention, motion of thetreadmill platform 204 has dimensions 5.08 cm in 0.5 secs minimum in alldirections. The maximum response time from trigger to release roller 210to cause a dynamic perturbation is preferably 100 msec, and the maximumresponse time to re-engage roller 210 to achieve total desiredperturbation motion is preferably 100 msec.

In one embodiment, a servo-driven rack-and-pinion drive 202 is providedfor lateral translation of the support surface. When coupled with theroller-clutch system 220 and the treadmill with lateral deck 200 itself,multi-axis perturbation is readily achieved and controlled. Thetreadmill with lateral deck 200 and motor drive 208 can attach to therack-and-pinion system 202 and rest on ultra-low friction plates 204 forunrestricted motion.

The present invention includes a novel system and method for deliveringthe controlled perturbations of the apparatus in FIGS. 1 and 15 atspecific timing based on event detection algorithms that provideinformation related to the kinematics of the user. The present inventionalso includes a novel apparatus and method for delivering the controlledperturbations of the apparatus at specific timing based event detectionof external triggers, such as a manual switch, audio cues, visual cues,or tactile cues. The perturbation system can be programmed to allowconstant or changing amplitude and constant or changing frequency ofperturbations that change from step to step or over a period of time. Inaccordance with the present invention, perturbations that require aresponse, such as a step, by the user but which do not necessarilyinduce a fall. These are imbalances for which the body must and doesrespond to, whatever their direction. In the preferred embodiment usinga motor drive 208, the magnitude and timing of the perturbationsdelivered by the roller/brake clutch mechanism 220 are pre-programmedfor the perturbation profiles desired.

Event detection algorithms 258 provide a trigger output that initiates aperturbation profile. FIG. 20 represents one embodiment of this novelsystem and method of detecting events and delivering controlledperturbations, whereby the roller/brake clutch system 220 in FIG. 15C isintegrated with a motor drive 208 and roller encoder 209 to provide thecontrolled perturbation together with event detection based on real-timefeedback from the components, external cues and specific timing relatingto various phases of the gait cycle, such as but not limited to heelstrike or toe off. When the event detection algorithm 215 detects atrigger, the prescribed perturbation is executed by the perturbationapparatus, for example, the motor drive 208 and the roller-clutch/brakemechanism 220 via the drive pulleys 213 and belt 211.

Detection of heel strike during walking can be used as an example todemonstrate the steps in the novel system and method for delivering thecontrolled perturbations included in an event detection algorithm. Theevent detection algorithm is programmed to issues trigger signal orsignals to deliver the prescribed perturbation at the 1^(st), 2^(nd),nth detected event, such as heel strike, or randomly selected based on anormal or other statistical distribution of detected events.Alternatively and additionally, the trigger can occur due to an externalinput such as from a switch. The process for determining when aperturbation should be delivered is shown in the flow chart of FIG. 17and is explained herein.

In one embodiment, heel strikes can be detected by monitoring motorcurrent. A graph of motor current 240 versus time can be seen in FIG.16. At the moment of heel strike 241, as in FIG. 16, there is ahorizontal resultant force that opposes the treadmill belt normalmovement resulting in a decrease in belt velocity. Toe-off 242 is alsoshown on graph 240. To maintain the belt at a constant velocity, themotor drive 208 increases the motor current to maintain the constantvelocity in the presence of the increased drag. This represents asignificant increase in motor current (I) with respect to time (dI/dt),which can be detected so that, for example, the positive peak in motorcurrent derivative (dI/dt) defines when the heel strike occurs.

FIGS. 18A-18F show various data derived from motor current motorposition which can be used to identify when a heel strike 241 or toe-off242 event has occurred thereby warranting delivery of a perturbation.FIGS. 19A-19B illustrate such identification of an event using motorcurrent only when heel strike 241 and toe-off 242 events occur resultingfrom the monitoring the motor current independently alone or togetherwith other variables such as the time rate of change of motor current.In this case, the moment of heel strike 241 and toe-off 242 can beascertained from monitoring the motor current parameter to identify thedetection event and cause a perturbation trigger.

In this embodiment, representationally shown in FIG. 17, the motorcurrent 250 is detected by a sensor 205 in FIG. 15B. This sensor 205 canbe any current monitoring sensor such a hall effect sensor. In oneembodiment, the output of sensor 205 is passed through an analog filter253, such as a single pole RC low pass filter with a −3 db point around10 Hz. The motor current signal 250 is preferably amplified by a gain,and offset relative the zero current output level of the sensor 205 and,in this embodiment, converted through analog to digital conversion 254to a digital signal for processing. This digital value is processedthrough a digital filter 255, such as a kernel smoothing algorithm whichapplies half sine coefficients over a variable width range of samples.The heel strike feature is detected from this smoothed output in theevent detection algorithm 258. In this case, heel strike is detected byfinding the positive peak of the current signal derivative 257.

Alternate variables that can be used independently or together with themotor current include motor voltage, and motor power. Each of thesemeasured or computed variables provides a time history that providesunique information about the loads and timing of loads applied to themotor 208, which in turn are representative of different phases of thegait cycle or other information relating to the gait cycle. Similarmeasurements and computational analysis for detecting kinematic eventscan be performed for loads placed on motors during motion of other bodyjoints other than lower extremity joints associated with gait. Forexample, motion of the trunk or upper extremity and phases of the suchmotion, such as shoulder kinematics or spinal kinematics, can bedetected by the algorithm of the present invention.

Additional embodiments for detection of kinematic events of thetreadmill apparatus incorporate data from other sensors 207 such aslinear or rotational encoders which provide data including but notlimited to velocity, acceleration, and jerk of the moving elements ofthe apparatus. These sensors 207 may be, for example, located on therollers 210 of the treadmill 200 or on other exercise equipment wherekinematic motion is measurable. For example, a rotational encoder 209may be attached to the roller drive 210 to record roller 210 and motor208 rotational displacement. The time rate of change of the roller drive210 and motor 208 rotational displacement is the rotational velocity 251in FIG. 17 and the time rate of change of velocity 251 is the rotationalacceleration 256. These data are used alone, or, as desired, fused withdata such as motor current 250 and time rate of change of motor current257 and other sensor 207 data output 252 and time rate of change of thisdata output 252 to provide more robust detection algorithms 258. Thesealgorithms may optionally use digital filtering 255, such as Kalman orcomplementary filters.

The detection algorithm 258 may use one or more of these variables. Forexample, linear and rotational encoder data from a motor combined withcurrent and derivatives of these data can be combined to create latentvariables, using Independent Component Analysis, Principal ComponentAnalysis or other data reduction techniques, on which feature extractionand feature detection can be performed to simplify data processing forthe detection algorithm. Other embodiments of the data algorithm 258 fordetecting gait phase events or events related to motion of a body jointincorporate Markov chains, Bayesian statistics, neural networks, orsimilar approaches that provide sensor fusion and real-time featureextraction.

Additionally, user input data 259, such as user body height, and weight,and/or an external switch, can be input as part of the event detectionalgorithm 258. When the event detection algorithm 258 detects an event260, a perturbation trigger 261 is initiated. In a preferred embodiment,the detection algorithm 258 detects and triggers a perturbation within40 ms of the detected event.

The event detection algorithm 258 also identifies events that can occuras a percentage of step time (e.g. mid-stance). In one embodiment, thisalgorithm is, based on average step time based on subject and walkingspeed during a warm-up phase. During this phase, each step is used(n>30) to determine an average step time. In one use method, the usercan select a percent of stance phase, or percent of average step time,at which to issue a trigger (eg. 0-100% from heelstrike to toeoff).Alternatively, such a trigger time can be selected randomly from between0-100% of the gait cycle from heel strike to toe off, including but notlimited to the braking phase and the propulsion phase of stance.Additionally, this gait phase detection system 200 can be used tocontrol and to change the treadmill speed based on braking phase (timeand force as measured by motor current and propulsion phase. If thebraking phase impulse is greater than propulsion phase impulse (adjustedfor treadmill running), then the treadmill belt (not shown) slows down.If the braking phase impulse is less than the propulsion phase impulse(adjusted for treadmill running), then the treadmill belt speeds up. Theapplication of perturbations at various phases of the gait cycle allowsfor training to modulate the stretch reflex/arc of the muscles crossinga body joint in the lower extremity. The same approach exists fortraining at different ranges of motion for a body joint in the upperextremity.

It should be understood that the algorithms of the present invention areexecuted by software that is located and stored on a storage device incomputer hardware. The computer hardware preferably includes the typicalstorage, such as hard drive, with operating system thereon, with memoryand input and output capability so computer data may be transferredbetween the computer running the algorithm and another electronicdevice. The sensors and other equipment electrically and physicallyinterface with the computer hardware. Any type of operating system andcomputer language may be employed.

The perturbations enable individuals to rapidly learn how to modifymotor performance Referring now to FIG. 21, the same perturbation forceFp applied at different phases of the gait cycle, represented here asknee angle theta, results in different forces F applied at the knee,which in turn causes different kinematic response of the knee and otherjoints. The anterior force F at the knee is dependent on the knee angletheta and the applied perturbation force Fp. For human locomotion, kneeangle during walking/running follows a very predictable pattern.Likewise, the perturbations can be applied to any joint based on thecurrent position, velocity, or acceleration of the joint, independent ofgait. This is particularly relevant for upper body neuromusculartraining paradigms.

The invention provides a method of providing a timed perturbation to theapparatus 10 or 200 based on external cues from a musical source orother external source (not shown). Music drives exercise profiles(speed, elevation, perturbation frequency/magnitudes, intensity, and thelike)—real-time modification of playlist based on what is being done.Music feedback can be used by the present invention as a behavioralmodifier.

In view of the foregoing, a new and novel system and apparatus isprovided that captures biomechanical data of body movement during adisturbance event, such as a slip or trip incident or other eventexperience by a part of the body. A disturbance event is simulated by atreadmill-based apparatus or other device. Data collected is used tocompute a wide array of parameters associated with body movement tobetter and more fully understand body movement during a disturbanceevent. Such parameters are to be studied to determine and evaluate stepresponses to a disturbance event. As a result, a new and novel method offall prevention training can be provided to the person to reduce thelikelihood of falling following a disturbance event. As a result, a newand novel neuromuscular training system for body joints can be provideto increase dynamic stiffness of the joint, and to reduce the likelihoodof injury to the joint caused by excessive motion.

It would be appreciated by those skilled in the art that various changesand modifications can be made to the illustrated embodiments withoutdeparting from the spirit of the present invention. All suchmodifications and changes are intended to be covered by the appendedclaims.

1. A method of training, comprising the steps of: providing a platformconfigured to support an individual standing thereon; moving theplatform, with the individual thereon, to allow the individual toachieve a continuous walking gait; monitoring the continuous walkinggait; identifying at least one portion of the continuous walking gait;when a selected one of the at least one identified portions of thecontinuous walking gait is detected, moving the platform to create adisturbance event having a duration of less than 500 ms that induces aresponse from the individual as part of a continuous walking gait. 2.The method of claim 1, wherein the platform is moved to create adisturbance event manually.
 3. The method of claim 1, wherein theplatform is moved to create a disturbance event at predeterminedintervals.
 4. The method of claim 1, wherein the platform is moved tocreate a disturbance event according to a preset script.
 5. The methodof claim 1, wherein portions of the continuous walking gait includeheelstrike, toeoff and stance phase.
 6. The method of claim 1, whereinthe portions of the continuous walking gait are detected by monitoringand detecting changes in movement of the platform.
 7. The method ofclaim 6, wherein changes in movement of the platform are monitored anddetected by monitoring and detecting current to a motor attached to theplatform for moving the platform.
 8. The method of claim 6, whereinchanges in movement of the platform are monitored and detected bymonitoring and detecting rotation of a spindle of a motor attached tothe platform for moving the platform.
 9. The method of claim 6, whereinchanges in movement of the platform are monitored and detected bymonitoring and detecting rotation of rollers attached to the platformfor moving the platform.
 10. The method of claim 5, wherein the stancephase further includes a braking phase, a midstance phase and apropulsion phase.
 11. The method of claim 1, wherein the disturbanceevent is created on every occurrence of the selected portion of acontinuous walking gait.
 12. The method of claim 1, wherein thedisturbance event is created on multiples of a selected portion of acontinuous walking gait.
 13. The method of claim 1, wherein thedisturbance event is created on a random number of occurrences of aselected portion of a continuous walking gait.
 14. The method of claim1, wherein the response from the individual is a change in activationpatterns of the musculature around body joints.
 15. A method oftraining, comprising the steps of: providing a platform configured tosupport an individual standing thereon; moving the platform, with theindividual thereon, to allow the individual to achieve a continuouswalking gait; monitoring kinematic variables associated with at leastone joint of the individual; identifying at least one kinematic variableassociated with the at least one joint of the individual; when aselected one of the at least one kinematic variables is detected andmeets a predetermined criteria, moving the platform to create adisturbance event having a duration of less than 500 ms that induces aresponse from the individual as part of a continuous walking gait. 16.The method of claim 15, wherein the disturbance event is created onevery detected occurrence of the selected kinematic variable.
 17. Themethod of claim 15, wherein the disturbance event is created onmultiples of a detected occurrence of the selected kinematic variable.18. The method of claim 15, wherein the disturbance event is created ona random number of detected occurrences of a selected kinematicvariable.
 19. The method of claim 15, wherein the response from theindividual is a change in activation patterns of the musculature aroundbody joints.
 20. A method of training, comprising the steps of:providing a platform configured to support an individual standingthereon; moving the platform, with the individual thereon, to allow theindividual to achieve a continuous walking gait; monitoring thecontinuous walking gait; providing triggering means to initiate movementof the platform to create a disturbance event; activating the triggermeans; monitoring the trigger means; detecting the trigger means; whenthe trigger means is detected, moving the platform to create adisturbance event having a duration of less than 500 ms that induces aresponse from the individual as part of a continuous walking gait. 21.The method of claim 20, wherein the trigger means is selected based on aperturbation profile for a given training activity.
 22. The method oftraining of claim 20, wherein the trigger means is selected from thegroup consisting of an event detection algorithm, switch, a musical cue,a visual cue and a tactile cue to initiate a disturbance event.
 23. Themethod of training of claim 22, wherein the event detection algorithm isbased on measured intrinsic physiological factors including both themagnitude and activation patterns of the musculature around the joints.24. The method of claim 20, wherein the disturbance event is provided ofvarying magnitude, direction and duration based on the timing of thetriggering means.
 25. A training apparatus, comprising: platformconfigured to support an individual standing thereon; the platform, withthe individual thereon, being configured to allow the individual toachieve a continuous walking gait; means for monitoring the continuouswalking gait; means for identifying at least one portion of thecontinuous walking gait; when a selected one of the at least oneidentified portions of the continuous walking gait is detected, meansfor moving the platform being configured to create a disturbance eventhaving a duration of less than 500 ms that induces a response from theindividual as part of a continuous walking gait.
 26. A trainingapparatus, comprising: a platform configured to support an individualstanding thereon; the platform, with the individual thereon, beingconfigured to allow the individual to achieve a continuous walking gait;means for monitoring the continuous walking gait; means for triggeringto initiate movement of the platform to create a disturbance event; whenthe trigger means is activated and detected, the platform moves tocreate a disturbance event having a duration of less than 500 ms thatinduces a response from the individual as part of a continuous walkinggait.
 27. A training apparatus, comprising: a platform configured tosupport an individual standing thereon; the platform, with theindividual thereon, being configured to allow the individual to achievea continuous walking gait; means for monitoring kinematic variablesassociated with at least one joint of the individual; means foridentifying at least one kinematic variable associated with the at leastone joint of the individual; when a selected one of the at least onekinematic variables is detected and meets a predetermined criteria,means for moving the platform being configured to create a disturbanceevent having a duration of less than 500 ms that induces a response fromthe individual as part of a continuous walking gait.